[Ground Illusion]

Hello everyone,
Haven't been able to post much lately because I have been slammed to the walls with springtime approaching rapidly. I am looking for a really good plant and tree identification book, and where it can be purchased. I have my good ol' Great Plant Guide from the American Horticultural Society, but I need more than that, and the internet just has to darn many to chose from. I would like to here from some other professionals what they like to use.